The present invention relates to an apparatus and method for automatically adjusting the recording speed of a recorder such as a video cassette recorder (VCR), wherein the recording speed is automatically changed by comparing the remaining length of a recording medium such as a tape with the remaining time of a program that is being recorded, thereby continuously recording the program.
In conventional VCRs, the recording speed such as SP, LP, or SLP is selected by a user in a normal recording function for directly recording the current broadcast signals, or a reserved (programmed) function for recording a desired program at a pre-programmed time using a timer. Once selected, the recording speed is maintained until completion of the recording unless the selected speed is changed. Therefore, when the broadcasting time of a program to be recorded is longer than that of the remaining tape which will be recorded, conventional recording is disadvantageous in that latter portions of the program to be recorded cannot be recorded due to the lack of tape, which thus results in an incomplete recording.
Several techniques have been proposed to overcome these disadvantages, which however, are insufficient to present a satisfactory solution.
More specifically, it is known to form an indicating groove in the cassette tape housing according to its tape length, i.e., for 30, 60, or 120 minutes. When a video cassette tape with the indicating groove is loaded, the programmed recording time is determined in the VCR by sensing the indicating groove, and then the recording speed is automatically set by comparing the kind of tape with the programmed recording time. However, this technique is used only for the reserved (programmed) recording function. Moreover, the indicating groove must be formed in the video cassette tape, which required an indicating groove sensing device in the VCR.
In addition to the above technique, a technique is suggested that the remaining tape is calculated by sensing a take-up reel pulse and a supply reel pulse, which in turn are converted into analog voltages to be compared with a preset voltage, thereby changing the recording speed. However, since the recording speed changing point is adapted by detecting an analog voltage in accordance with a preset value, malfunction frequently occurs when a inaccurate reference voltages are set by the user.